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Up andComing: Checking inWith theNextGenerationpage 5

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For JQI research news, see http://jqi.umd.edu, updated daily.

Institute News for January 2010

Oxford Instruments service engineer David March checks the business end of the new JQI-PFC dilution refrigerator. ►

The Big ChillTemperatures have been dropping fast this winter. But noth-ing like this: On Monday, Jan. 4, engineers from Oxford Instru-ments uncrated the components for a new dilution refrigera-tor. By Wednesday it was fully assembled in renovated lab facilities on the first floor of the University of Maryland’s Toll Physics Building, and by Thursday it had already hit 20 milli-kelvin -- about a hundred times colder than interstellar space.

JQI and its Physics Frontier Center will use the “dil fridge” to experiment with a novel concept for a hybrid quantum infor-mation processor that combines the speed and sensitivity of superconducting circuits with the comparatively long quan-tum memory of trapped atoms. That arrangement requires very low temperatures, as well as several exotic, high-tech continued, page 3

UMD Gets $10.3 Million to Fund 21,000 SF of High-Tech Quantum Science Labs

The National Institute of Standards and Technology has awarded the University of Maryland at College Park $10.3 million for construc-tion of the Laboratory for Advanced Quantum Science (LAQS). Coupled with an ad-ditional $5.2 million from the university, the total project budget will be $15.5 million. continued, page 6

New lab space will be underground at the planned Physical Sciences Complex

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JQI Co-Director Carl J. Williams, Chief of the Atomic Physics Division at the National Insti-tute of Standards and Technology, has been

named a Fellow of the American Asso-ciation for the Advancement of Science.

Williams was cited for “distinguished contributions to the theory of cold atom collisions and small molecule spectroscopy, in particular to ultracold photoassociation spectroscopy and dynamics of ultracold gases.” AAAS notes that the newly named Fellows “will be recognized for their contribu-tions to science and technology at the Fellows Forum to be held on 20

February 2010 during the AAAS Annual Meeting in San Diego. ”

Carl Williams Named AAAS Fellow

Three JQI Fellows Receive NIST Bronze MedalsCharles C. Clark, Alan L. Migdall and Ian B. Spielman of the National In-stitute of Standards and Technology have been awarded the Departmental Bronze Medal, NIST’s highest honor.

Among other accomplishments, the award recognizes “significant con-tributions affecting major programs [and/or] scientific accomplishment within the Institute ...”

Clark (top at right) was honored for “development of a new detector of neutrons.” Migdall (center) was cited for “advancing photon-based metrology for applications in optical radiation measurement, fundamental physics and quantum radiation.” Spiel-man (bottom) received the award for “development of methods to simulate condensed-matter models by creating simple experimental realizations using ultracold atomic gases.”

Alumni NewsChad Orzel, who got his PhD in chemical physics (UMD ‘99) with the Laser Cooling and Trapping Group at NIST, now teaches physics at Union College in Schenectady, NY. Last month he published “How to Teach Physics to Your Dog,” (Scribner, 256 pp.).

Orzel also writes a lively blog titled “Uncertain Principles: Physics, Politics, Pop Culture,” which can be found at http://scienceblogs.com/principles/.

Orzel and Emmy, the Teacher’s Pet

Carl J. Williams

Fridge, from page 1

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conditions that have never been combined in the planned configuration.

The idea is to create a qubit (that is, a quantum “bit,” or information unit, which instead of having a single value can exist in a superposition of mul-tiple values simultaneously until it is measured) using superconducting circuit loops, and then to couple the qubit to the state of a nearby atom. The properties of the qubit circuit affect the atom’s magnetic orientation, in effect transferring the indeterminate qubit state of the circuit to the atom, making the magnitude and direction of the atom’s magnetic field correspondingly indeterminate.Creating qubits with superconducting circuits is a familiar, if highly deli-cate, process. The circuit loops are punctuated at intervals by tiny tunnel barriers called Josephson junctions. Current can flow through the junc-tions with no voltage drop. Under certain circumstances, the current can flow clockwise or counterclockwise around a loop with equal probability; and owing to the peculiar nature of quantum reality, the system exists in a superposition of both directions until it is measured. The act of mea-surement forces the system to take on a specific state. But until then, the qubit’s state is an indeterminate superposition. So if, prior to measurement, the qubit is coupled to another object (in this case, an adjacent atom) then the atom, too, can be in a superposition of states.

For this to happen, however, the atom has to be extremely close to the superconducting circuit -- within a couple of micrometers (millionths of a meter) -- and it has to be held nearly motionless. The JQI team -- which includes Fellows Bob Anderson, Alex Dragt, Chris Lobb, Luis Orozco, Steve Rolston, Jake Taylor and Fred Wellstood, with assistance by Carl Williams and Eite Tiesinga -- will attempt that by using a precision-tapered optical fiber that is about 0.2 micrometers wide at its thinnest point, as depicted below.

In the planned experiment, which is supported by the National Science Foundation through JQI’s Physics Frontier Center, light of different frequencies (shown as red and blue waves above) will interfere and create a pattern of high and low intensity that can trap atoms just outside the thin optical fiber. Rubidium atoms will settle into the lowest-energy nodes, and the fiber will then be brought within a few micrometers of the superconducting qubit, marked with a red cross in the drawing. One key challenge in this part of the experiment is that the fiber assembly has to be designed so that it does not add too much heat to the envi-ronment. But the extremely narrow tapered fiber is not expected to do so, even in close proximity.

If researchers can learn to manipulate the atoms satisfactorily, control sources of decoherence in the qubits and couple the qubits to the atoms as desired, the array can be used as a quantum information processor

Oxford engineer Nick Dentadjusts the spacing aroundthe fridge compressor unit.

Fridge, from page 1

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Time after TimeTime magazine, which cited the teleportation demonstration reported by JQI Fellow Chris Monroe and colleagues (“Quantum Teleportation Between Distant Matter Qu-bits,” S. Olmschenk, D. N. Matsukevich, P. Maunz, D. Hayes, L.-M. Duan and C. Monroe, Science 323, 486) in its “50 Best Inventions of the Year,” has now placed the work at No. 8 in the “Top 10 Scientific Discover-ies of 2009.”

In the latest list, JQI teleportation lagged behind tank-bred tuna (at No. 5) and water on the moon (No. 6), but it edged out the Large Hadron Collider’s post-repair beam-up (No. 9) and the discovery of a ”planetlike” object orbiting a sun-like star (No. 10).

in which operations are performed by the ultra-fast superconducting qubits and the results are “written” onto the rubidium atoms.

To cool the qubits, the experiment requires temperatures achievable by a dilution refrigerator, which takes advantage of an interesting property of helium. When a mixture of two isotopes (helium-3 and slightly heavier helium-4) is cooled below about 0.87K, it separates into two distinct “phases,” one with a high concentration of He-3 and one with a lower concentration, somewhat analogous to the density dif-ference between water and steam. Just as a pool of water is cooled when the hottest water molecules es-cape the liquid and pass into the gas phase, the “evaporation” of He-3 from the more condensed phase to the more dilute phase carries heat away. This action can be used to lower the temperature to something in the range of a few one-thousandths of a degree (or millikelvin).

Many older dil fridges have to be constantly replenished with liquid helium in order to operate. The new Oxford Instruments model uses a closed-cycle cryo-cooler to cool the dil fridge, thus reducing the cost of operation.

Detail ofdilutionrefrigeratorapparatus

Left: JQI FellowsFred Wellstoodand Chris Lobb, among others, willuse the new device. Right: The base of the coolingunit with enlarged detail of theheat-exchangecomponents. Low temperatures are achieved when a light isotope of helium “evapo-rates” from one phase to another carrying away heat in the process.

Up and Coming: E. Goldschmidt

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JQI Graduate Fellow Elizabeth Goldschmidt believes that quan-tum mechanics is “hard to understand, but easy to use.”

You’d certainly never know it, however, from her principal re-search project: a ferociously difficult attempt to create solid-state quantum memory using a tiny crystal of yttrium orthosilicate (YSO) doped with ions of praseodymium -- a rare-earth metal with a very narrow and very faint transition signature. But then Goldschmidt has been looking for this kind of challenge for a long time. Early in high school, the Chicago native started reading books by Brian Greene and Stephen Hawking at the urg-ing of a family friend who had always wanted to be a physicist but ended up as a pathologist. During her undergraduate years at Harvard (which included a summer stint with the CDF team at Fermilab), she decided on AMO physics because “you could do tabletop experiments with one or two other people, not like CERN.”

After graduating in 2006, she spent 10 months with the Henry L. Stimson Center, a Washington think-tank, doing homeland security research. “I wanted to take some time off to get a break and to make sure that physics was really what I wanted to do. I have always been interested in policy and

I thought it would be interesting to work at a place like the Stimson Center. I am very glad that I did it because now I know that I definitely want to be

in physics! The work was interesting, and it really helped my writing skills. But I just found that the atmosphere was not for me, I didn’t really like the formal office environment and the research was too soft. I like being in research where your argument is only as good as your data.”

So she looked at graduate schools, and was immediately drawn to UMD. And, in particular, to JQI: “It had a really nice feel, a great reputation, and there were just tons of people doing interesting work.” Since 2007, she’s been a graduate research assistant at NIST, supervised by JQI Fellow Alan Migdall. Last fall she also served as a teaching assistant with JQI Co-Di-rector Steve Rolston. A committed fan of city life, she lives in the District’s Mount Pleasant neighborhood.

At NIST, she anticipates a few more years wrestling with the eccentrici-ties of Pr-doped YSO. It behaves much like a free-atom system, and could

provide coherent memory times of up a second -- an enormous interval for such materials. But to do so, the crystal has to be treated with multiple laser beams, including a 606 nm beam from an orange dye laser. The frequency will have to be stabilized and exquisitely fine-tuned to trigger a hyperfine transition in the Pr ion. “The transition is very weak -- which is why it’s got such a long lifetime,” Goldschmidt says. “That’s a huge advantage. The drawbacks are ... everything else.”

Up and Coming is a regular monthly feature profiling JQI’s young researchers.

Above right: Tending the dye laser. Above left: Checking coolant feed to the sample enclosure. Right: The specially fabricated, Pr-doped YSO crystal, approximately 10 mm long and 2 mm wide, is shown next to a dime.

LAQS Funding, from page 1

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The grant will provide JQI scientists and other investigators with state-of-the-art facilities as good as any in the world, by adding 21,000 square feet of underground laboratory space that is specifically designed for the needs of research at the frontiers of quantum science. The facilities will be constructed beneath UMD’s planned Physical Sciences Complex, which will be attached to the east side of the Computer and Space Sciences Building (site of the current JQI headquarters) and will occupy the space currently devot-ed to a parking lot.

“These world-class labs will keep JQI at the forefront of quantum science,” said JQI Co-Director Steven Rolston. “We are deeply grateful for the opportunity this award makes possible, and we intend to produce results that will fully justify the confidence that NIST has shown in our research goals and capabilities.”

LAQS will feature environmental controls for clean air, low vibration and electromagnetic interference, as well as stable temperature and humidity, that meet the exacting standards of the Advanced Measure-ment Laboratories at NIST (see box below), which are widely regarded as the most sophisticated facilities of their kind.

LAQS will primarily support the work of the JQI scientists whose work focuses at the intersection of three fast-moving research areas: atomic, molecular and optical physics; condensed matter physics; and quan-tum information science. The most advanced experimental work in those fields demands exquisitely fine control of the research space. Many instruments, such as precision lasers, must be protected from even tiny vibrations and operated in an environment that restricts thermally induced expansion or contraction to less than a few billionths of a meter.

Construction of the Physical Sciences Complex, including the LAQS, is expected to begin this year and to be completed by spring 2013.

The NIST award is part of a $123 million package of grants announced Jan. 8 in response to the American Recovery and Reinvestment Act, providing funding to 11 universities and one nonprofit research organi-zation for construction of new scientific research facilities.

The agency statement notes that “with ultimate research targets ranging from off-shore wind power and coral reef ecology to quantum physics and nanotechnology, the 12 projects will launch more than $250 million in new laboratory construction projects beginning early this year.”

Some of NIST’s AML Specifications

Recent Publications

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“Protocol for Hybrid Entanglement Be-tween a Trapped Atom and a Semiconduc-tor Quantum Dot,” E. Waks and C. Monroe, Phys. Rev. A 80, 062330 (2009).

“Optical Shockley-like surface states in photonic superlattices”, N. Malkova, I. Hro-mada, X. Wang, G. Bryant, Z. Chen, Optics & Photonics News 20, 23 December 2009.

“Protocols and Techniques for a Scalable Atom- Photon Quantum Network,” L. Luo, D. Hayes, A. Manning, D.N. Matsukevich, P. Maunz, S. Olmschenk, J.D. Sterk, and C. Monroe, Fortschritte der Physik 57, 1133-1152 (2009).

“Demonstration of a scalable, multiplexed ion trap for quantum information pro-cessing,” D.R. Leibrandt, J. Labaziewicz, R.J. Clark, I.L. Chuang, R.J. Epstein, C. Os-pelkaus, J.H. Wesenberg, J.H. Bollinger, D. Leibfried, D. Wineland, D. Stick, J. Sterk, C. Monroe, C.-S. Pai, Y. Low, R. Frahm, and R.E. Slusher, Quant. Inf. Comp. 9, 901 (2009).

“Mesoscopic Effects in Quantum Phases of Ultracold Quantum Gases in Optical Lat-tices,” D. Carr, M. L. Wall, D. G. Schirmer, R. C. Brown, J. E. Williams, and C.W. Clark has been accepted at Physical Review A.

“Improved Timing Resolution Single-Photon Detectors in Daytime Free-Space Quantum Key Distribution with 1.25-GHz Transmission Rate,” A. Restelli, J. C. Bien-fang, C.W. Clark, I. Rech, I. Labanca, M. Ghioni and S. Cova, has been accepted for publication in the Journal of Selected Top-ics in Quantum Electronics.

“Ultracold dipolar molecule formation by first loading onto an optical lattice,” J.K. Freericks, M.M. Maska, A. Hu, T.M. Hanna, C.J. Williams, P.S. Julienne and R. Lemanski has been accepted as a Rapid Communi-cation in Physical Review A.

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PUBLICATION IMAGE OF THE MONTH: The figure above appears in “Radio-frequency dressing of mul-tiple Feshbach resonances,” A.M. Kaufman et al, Phys. Rev. A 80 050701 (R) (2009). JQI co-author Tom Hanna of NIST explains it this way:

The figure illustrates the use of radiofrequency radia-tion (RF) along with magnetic field to control the scat-tering properties of ultracold rubidium atoms. The rate of atom loss is shown as a function of magnetic field (vertical axis) and frequency of RF radiation (horizon-tal). Many experiments in cold gases make use of reso-nances in the scattering properties that can be tuned with a magnetic field. The broad yellow band is the normal, magnetically tuned resonance that would be observed without RF. With the RF on, however, several other states are coupled which can cause resonances of their own, giving the complicated structure shown here. The color plot is the result of a calculation by my-self and JQI fellows Eite Tiesinga and Paul Julienne. The predicted locations of maximum rates of loss agree with observations by David Hall’s experimental group at Amherst College, shown as black dots.

This work demonstrates, for the first time, the utility of RF for controlling scattering properties. It presents the possibility of tuning scattering lengths between vari-ous components of a multicomponent gas, or tuning scattering lengths with greater speed and precision than magnetic fields alone allow. These capabilities could further studies in quantum information, as well as few- and many-body physics in ultracold gases.

JQI is a joint venture of the University of Maryland and the National Institute of Standards and Technology, with support from the Laboratory for Physical Sciences.

Joint Quantum InstituteCSS (Bldg. 224) Room 2207University of MarylandCollege Park, MD 20742E-mail: jqi-info@umd.edu

Entangled States

JQI Fellow Charles Clark has been named to the National Science Foundation’s Alan T. Water-man Award Committee. The Waterman award is presented annually to “recognize an outstand-ing young researcher in any field of science or engineering supported by the National Science Foundation.” Clark will be the speaker at the UMD Physics Department Colloquium on Jan. 26.

On Dec. 15, JQI Fellow Bill Phillips went to Eleanor Roosevelt High School in Greenbelt, MD to conduct a “Science Cafe” session involving an informal talk for students and a more formal, “community” lecture.

On Jan. 4, JQI Fellow Paul Julienne gave an invited talk at the Physics of Quantum Electronics conference in Snowbird, UT, titled “Universal reac-tion rates for ultracold molecular collisions.”

JQI’s Josh Bienfang is interviewed on an enlight-ening video that is part of SPIE’s contribution to the 50th anniversary of the laser. Bienfang dis-cusses the use of lasers in quantum cryptography at: http://spie.org/x38723.xml?ArticleID=x38723

◄ At a Nov. 10, 2009 reception for Ameri-can Physical Society Fellows in the Wash-ington, DC region, Charles Clark ran into Spectra, “the original laser superhero,” as embodied in Rebecca Thompson-Flagg -- Head of Public Out-reach for APS. (JQI Fellow Wendell Hill can be seen above Spectra’s left shoul-der. ) Below is the APS comic book published to usher in the 50th anniversary of the laser, and to coincide with the year-long celebration called LaserFest, sponsored by APS, the Optical Society of America and IEEE Photonics.

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